Was hoping to get some help regarding a strange issue I'm having with two touch screens I ordered. These are the screens, http://www.dealextreme.com/p/sony-ericsson-x1-replacement-touch-screen-digitizer-module-32335
I ordered a DS connector from sparkfun, created my own breakout board. I've been utilizing this tutorial http://kalshagar.wikispaces.com/Arduino+and+a+Nintendo+DS+touch+screen
and the full explanation from the book Practical Arduino: Cool Projects for Open Source Hardware
Chapter 8: touch control panel (safari ftw). I've tried the code in the book, the code from kalshagar's site, and ladys touchscreen.h library.
This was originally wired up to a project I am working on that is currently a boarduino. I've tested the code from each of the above references on my original arduino atmega328 and the megas I ordered and burned thinking maybe I did something wrong fuse wise etc...
What is happening is the output readings from both touchscreens on either my boarduino setup or the original arduino aren't true cartesian coordinates. This is sitting on top of a KS0108 GLCD with 8 buttons on it. If I use my stylus and draw horizontally across the screen both x,y change as I move!
and not like... a little just from natural hand movement. Would post exact output but currently at work. I know for a fact moving horizontally a little over and inch resulted in about a 20-25 in deviation on x and y, almost as though I was actually drawing diagonally. It changes drastically under a full sweep of x or y.
I've adjusted the code from each example thinking it was possibly the touch screens them selves. I've followed this documentation as well for a better understanding http://www.sparkfun.com/datasheets/LCD/HOW%20DOES%20IT%20WORK.pdf
and thought maybe the screen needed to read from a specific bar so I tried reading from 1 instead of 3 and 0 instead of 2 (zero indexing the pins to match them on the mega) both end in the same result.
I'm using analog inputs 0-4, I've made sure I reference them as A0-A4 in the code, I'm making sure my digitalWrites correspond to the pin numbers as well since they are different (I ref the pin number directly, e.g. 14 for A0)
Any help would be greatly appreciated, oh I also tried it with and without the pulldowns, same result. I can post all code examples etc when I get home unless someone has seen this strange output before.. or maybe its just me :-)